Re: newrole - adding capabilities for polyinstantiation

[Michael C Thompson <thompsmc@us.ibm.com>]

Stephen Smalley wrote:
> On Wed, 2006-10-04 at 11:31 -0500, Michael C Thompson wrote:
>> Stephen Smalley wrote:
>>> That is not correct.  File system operations in Linux are based on the
>>> fsuid, which shadows the euid unless explicitly set.
>> hmm, you are right (and I, alas, was wrong). However, the files will be 
>> created with the egid being the calling user (as it stands). I imagine 
>> we'd want to change that.
> 
> Not clear that it matters.  IIUC, pam_namespace already sets the user
> and group ownership after creation, so the only reason we care about
> euid/fsuid is ensuring that the directory isn't temporarily accessible
> to the caller.  As long as the directory mode is owner-only (as I think
> it is), the initial gid on the directory shouldn't matter.
> 

 From pam_namespace.c:
mkdir(ipath, S_IRUSR)

After this, the security attributes of the directory are set according 
to those of the original with the appropriate uid/gid and perm mask.

So again, you are indeed correct. One of these days...!

Mike


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